GB2388890A

GB2388890A - A needle valve

Info

Publication number: GB2388890A
Application number: GB0229663A
Authority: GB
Inventors: Roland Casar; Jan Gartner; Frank Obrist; Jurgen Wertenbach
Original assignee: Obrist Engineering GmbH; DaimlerChrysler AG
Current assignee: Obrist Engineering GmbH; Mercedes Benz Group AG
Priority date: 2001-12-22
Filing date: 2002-12-20
Publication date: 2003-11-26
Anticipated expiration: 2022-12-20
Also published as: US6991212B2; DE10163929A1; US20030116734A1; GB2388890B; GB0229663D0

Abstract

The needle valve 1 for a high-pressure gas conduit system consists of two mounting units 2, 3 capable of being plugged together. One of the mounting units surrounds, in its housing 7, a stepping motor 8, and a valve needle 10 projecting away from the said mounting unit is intended for sealing engagement into a guide bore of the housing block 4 of the other mounting unit. The inner region, receiving the gas pressure and having the valve duct 17, of the housing block 4 is thus sealed off relative to the outside by means of sealing rings 19, 20 such as O-rings arranged in the region of the guide bore. By virtue of a small diameter of the guide bore which corresponds at least approximately to the diameter of the valve duct 17, good sealing-off is obtained. The needle valve 1 is suitable, in particular, as an expansion valve, capable of having a flow passing through it in both directions, of a vehicle air-conditioning system operated with carbon dioxide.

Description

GB 2388890 A continuation (72) Inventor(s): Roland Casar Jan Gartner Frank

Obrist Jurgen Wertenbach (74) Agent and/or Address for Service: Jensen & Son 366-368 Old Street, LON DON, EC1 V SILT, United Kingdom

( A needle valve The invention relates to a needle valve for a highpressure gas conduit system, with a housing block having connecting bores for pipe portions of the gas conduit system, a valve duct connecting these connecting bores and a socket coaxial with the said valve duct, a valve needle intended for engagement into the valve duct and connected to a stepping-motor drive being led through the socket.

For regulating the expansion valve of air-conditioning systems it is known from EP O 607 953 and WO 00/70276 to arrange the valve drive or a part of the latter connected mechanically to the valve needle in a housing which is connected to the housing block of the valve in a gas- tight manner. This method of sealing off the inner region of the housing block relative to the outside presupposes that the parts of the valve drive, such as, for example, the armature winding of the latter, are not attacked by the medium enclosed in the expansion valve. Moreover, a pressure-resistant design of the drive housing presupposes a suitably dimensioned robust form of construction It is known, furthermore, from US 3,464,227 and US 4,556,193, to connect the shank of the valve needle or of the closing body of the expansion valve of an air-conditioning system to the housing block in a gas-tight manner via a concertina. Concertina- type sealing-off is suitable only for relatively low gas pressures and, to be arranged in the housing block of the needle valve, requires a space which codetermines the overall dimensions of the housing block.

The present invention seeks to find a valve having as small dimensions as possible, which is suitable for high pressures and has a throughflow in two directions opposite to one another and which can also be used as an expansion valve of an air-conditioning system operated with carbon diode, that is to say for pressures up to 150 bar.

Moreover, along with a capacity for simple production, it is to allow a design which simplifies mounting in the conduit system of a vehicle airconditioning system.

/ According to the present invention there is provided a needle valve for a high-pressure gas conduit system, with a housing block having connecting bores for pipe portions of the gas conduit system, a valve duct connecting these connecting bores and a socket coaxial with the said valve duct, a valve needle intended for engagement into the valve duct and connected to a stepping-motor drive being led through the socket, wherein the inner region, receiving the gas pressure, of the housing block is sealed off relative to the outside by means of at least one sealing ring which surrounds the valve needle in the region of a guide bore.

Preferred embodiments of the invention are the subject-matter of the subsidiary patent claims and are now described with reference to the drawings in which Fig I shows a perspective illustration of the housing of a stepping-motor drive, with a connected valve needle, corresponding to a first mounting unit, Fig. 2 shows a perspective illustration of the housing block of the needle valves corresponding to a second mounting unit, Fig. 3 shows an overall perspective illustration of the needle valve with its mounting units according to Figs. 1 and 2 which are mounted against one another, Fig. 4 shows a cross section through the needle valve according to Fig. 3, Fig. 5 shows a cross section through another embodiment of the needle valve, Fig. 6 shows an enlarged partial illustration in the area V] of the cross-sectional illustration of Fig. 4, with the valve needle in the uppermost position, Fig. 7 shows an illustration corresponding to that of Fig. 6, but with a modified version of the housing block and with the valve needle in the closing position, Fig. 8 shows a side view of an embodiment of a valve needle differing from the valve needle shown in Figs. 6 and 7, and

l Fig. 9 shows a further embodiment of a valve needle.

The needle valve I consists of two releasably interconnected mounting units 2 and 3, the first of which consists of a housing block 4 having a plurality of bores and formed, for example, from a portion of an extrusion profile and is provided for the connection of pipe portions 5, 6 of a high-pressure gas conduit system. The second mounting unit 3 surrounds, in a drive housing 7, a stepping motor 8 with a drive mechanism 9 for the valve needle 10 in a version which is known per se. A drive nut, not illustrated, capable of being set in rotation by means of the motor, engages correspondingly into the external thread II of the valve needle 10. Since this valve needle is secured against rotation at its profiled upper end 12, this gives rise to its longitudinal movement necessary for valve actuation. The valve needle 10 is therefore an integral part of the second mounting unit 3. The two mounting units 2 and 3 can be assembled in a simple way to produce the ready-to-use needle valve 1, as is described in more detail below.

The ends of the pipe portions 5, 6 are held in a gas-tight manner in connecting bores 13, 14 of the housing block 4, in that they are soldered in there according to the embodiment shown in Fig 5 or in that the connecting bores 13, 14 form a spigot receptacle for the releasably insertable pipe spigot of a pipe coupling which carries sealing rings, such as is described in more detail in German Patent Application DE IOI 63 931.7. The connecting bores 13, 14 merge into short valve conduits 15, 16 respectively, which are designed as blind holes. These have a substantially smaller diameter and are transversely offset to one another, so that they overlap one another.

The valve duct 17 forms a right-angled cross connection between these valve conduits.

It goes without saying, however, that, instead, the valve duct 17 may Nan at an inclination to the valve conduits 15, 16, for example in order to eliminate a generation of noise caused by the right-angled change in direction of the flow.

In the embodiment according to Fig. 4, the transverse offset in the case of coaxial connecting bores 13, 14 is achieved in that the said valve conduits are continued eccentrically to these or in an axially offset manner. In the embodiment according to Fig. 5, the valve conduits 15, 16 run coaxially with the connecting bores 13, 14

provided for the pipe portions 5, 6, so that the said connecting bores run at an axial offset to one another. The capacity for simpler production of coaxial bores 13, 16; 14, 15 has the disadvantage, however, that the housing block 4' cannot be mounted in different angular positions in relation to a pipeline axis.

The valve needle 10 drive-connected to the stepping motor 8 extends into the housing block 4 through a guide bore 18 running coaxially to the valve duct 17. The stepping motor 8 makes it possible to adjust the said valve needle continuously in the guide bore 18, so that the free opening cross section of the valve duct 17 can be varied continuously between a minimum and a maximum value. i The necessary sealing-off of the inner region, formed by the bores 15, 16 and the central valve duct 17, of the housing block 4 relative to the outside takes place, according to the invention, in the region of this guide bore 18, in that at least one sealing ring, in this embodiment shown as two rings 19, 20, is provided there.

In order to achieve good sealing-off with respect to carbon dioxide which is under high pressure, at a relatively low outlay in structural terms, without excessive frictional resistances occurring during the adjusting movement of the valve needle, the two O-

rings 19, 20 are provided at a distance from one another and are preferably held in peripheral grooves 21, 22 of the valve needle 10.

In the embodiment according to Fig. 7, the receiving grooves 23, 24 for two O-rings 25, 26 are provided in the guide bore 18, but this leads to a higher outlay in terms of the machining of the housing block 4 and to a somewhat larger diameter of the O-rings 25, 26. The sealing-off in the region of the guide bore 18 by means of O-rings 19, 20; 25, 26 also has, inter alla, the advantage of a substantially easier mounting of the needle valve 1 in a gas conduit system, for example in the engine space of a vehicle, in that, during the mounting of the gas conduit system, first only the housing block 4 has to be inserted between two pipe portions S. 6 and the subsequent completion of the needle valve I may take place simply by the drive housing 7 connected to an electrical junction dead 28

( being put in place and at the same time the valve needle 10 being pushed into the guide bore 18. Finally, a fimn connection is made by means of four screws 29 which extend through corner regions of the parallelepipedic drive housing 7 into correspondingly arranged threaded holes of the housing block 4, so that the flange surfaces 30, 31 of the two housings 4, 7 come to bear firmly against one another.

The guide bore 18 may extend as far as the flange surface 31, facing the drive housing 7, of the housing block 4 and thus at the same time forms a socket for the valve needle 10, or, according to the exemplary embodiment illustrated, the housing block 4 has provided in it a socket 32 of larger diameter for a cylindrical housing extension 33 of the drive housing 7, the said housing extension surrounding part of the drive mechanism 9 of the stepping motor 8. The latter version is to be preferred, since the drive housing 7 can thereby be dimensioned smaller. Sufficient space for a correspondingly larger socket 32 is available in the housing block 4 when engagement bores 34, 35 are to be provided laterally in the housing block 4 for the fastening of the side flange of a pipe coupling adjoining the pipe portions, according to German Patent Application 101 63 931.7.

In order to make the sealing limit, that is to say the surface along which frictional sealing contact is necessary, small, so that the stepping motor, together with its housing 7 surrounding the drive system, can also be made smaller, the valve needle 10 and consequently also the guide bore 18 are provided with as small a diameter as possible. If there is no need for a completely leak-tight closing of the needle valve 1, for example when it is used as a regulatable expansion valve of a CO2 airconditioning system, the guide bore 18 preferably has the same, small, diameter as the valve duct 17. For a sealing seat by means of a conical end region 36 of the valve needle 10, a 15 to 20% larger diameter of the guide bore 18 and a corresponding diameter of the cylindrical part of the valve needle 10 may be sufficient.

Since there is no need for a complete closing of the expansion valve when the needle valve 1 is used as an expansion valve of an air-conditioning system, the diameter of the valve duct 17 and consequently also of the guide bore can be reduced, according to the embodiment shown in Fig. 7, in that a part-stream is led past the valve duct 17 through a

! bypass duct 37. For this purpose, for example, the bore of the valve duct 16 located on the low-pressure side is continued coaxially, with a substantially smaller diameter, into the bottom space 38 of the opposite connecting bore 14.

Furthermore, a bypass connection may also serve for relieving the sealing region of the guide bore 18, in that within the guide bore 18, according to the illustration in Fig. 7, and/or at a corresponding position of the valve needle 10" which is in the closing position is provided a peripheral groove 40 or 41 which is connected via a bore 42 to the bottom space 43 of the connecting bore 13 located on the low-pressure side. Instead or in addition, a bypass duct 39 may also be led through the valve needle 10', as shown in the cross-sectional illustration of Fig. 9.

A further measure for making the diameter of the valve duct 17 and consequently also that of the guide bore 18 as small as possible is that the valve needle 10 can be moved with its tapering front end 36 out of the valve duct 17, so that the opening cross section of the latter is released completely.

Finally, the throughflow of the valve duct 17 can be assisted by a conical or curved design of its orifice edges 27, 27', so that a better utilization of the cross-sectional size of the valve duct 17 is obtained. Also, as a result, noises caused by the throttling of the flow in the region of the valve duct 17 can be reduced or eliminated.

For pipeline systems which, including their electrical junction connection 28, may be damaged, for example, due to the action of a crash, so that there is a risk caused by outflowing medium, the housing 7 of the stepping motor 8 may have provided in it an emergency power-generating system 44 with an electrical energy store and with control electronics which are programmed, in the event of an interruption in a main power supply to the stepping motor 8, to make an emergency power connection between the latter and the electrical energy store for the purpose of closing the needle valve 1

Claims

1. A needle valve for a high-pressure gas conduit system, with a housing block having connecting bores for pipe portions of the gas conduit system, a valve duct connecting these connecting bores and a socket coaxial with the said valve duct, a valve needle intended for engagement into the valve duct and connected to a stepping-motor drive being led through the socket, wherein the inner region, receiving the gas pressure, of the housing block is sealed off relative to the outside by means of at least one sealing ring which surrounds the valve needle in the region of a guide bore.

2. A needle valve according to Claim 1, wherein a connecting bore is provided

coaxially as a blind-hole bore in each case for the pipe portions of the gas conduit system on sides of the housing block which are located opposite one another, the said connecting bores in each case extending towards the valve duct via an axially parallel mutually overlapping valve conduit of smaller diameter, so that the valve duct forms a crossconnection between the two.

3. A needle valve according to Claim 2, wherein the coaxial connecting bores form a spigot socket for the engagement of a coupling spigot of a releasable pipe coupling, the said coupling spigot having sealing means.

4. A needle valve according to Claim 3, wherein at least one bore for the engagement of fastening means of a side flange of the pipe coupling is provided, parallel to the respective spigot socket, in the housing block.

5. A needle valve according to any one of Claims 1 to 4, wherein the housing block is formed from a portion of an extrusion profile, the cross section of which widens from a narrower region, provided for receiving the connecting bores, in the direction of a flange surface which is intended for connection to the housing of the stepping motor.

6. A needle valve according to any one of Claims 1 to 5, wherein the stepping motor is enclosed in a second housing block which is connected releasably to the other

( 8 housing block enclosing the valve duct, so that the housing blocks in each case form a mounting unit, of which one has pipe portions of the gas conduit system and the other has an electrical junction lead serving for controlling the stepping motor, the valve needle being assigned to the mounting unit of the stepping motor by means of an engagement connection with the drive mechanism of the latter.

7. A needle valve according to any one of Claims I to 6, for an airconditioning system operated with carbon dioxide, wherein the guide bore serving for sealing contact with the valve needle has at least approximately the same diameter as the valve duct.

8. A needle valve according to any one of Claims I to 7, wherein the at least one sealing ring is an O-ring.

9. A needle valve according to any one of Claims 1 to 8, wherein the at least one sealing ring is held in a groove surrounding the valve needle.

10. A needle valve according to any one of Claims 1 to 9, wherein the valve needle is surrounded by two sealing rings.

11. A needle valve according to any one of Claims 1 to IO, wherein, with the valve opened to the maximum, the front end of the valve needle is at a distance from the valve duct, so that the opening cross section of the latter is completely free.

12. A needle valve according to any one of Claims 1 to 7, wherein a bypass connection of smaller cross section is provided in relation to the valve duct.

13. A needle valve according to Claim 8, wherein between a region of the guide bore surrounding the valve needle and a low-pressure region of the needle valve is provided a compensating connection serving for the relief of pressure at the sealing region of the guide bore, this region being arranged between the at least one sealing ring and the adjacent valve conduit.

14. A needle valve according to Claim 13, wherein the compensating connection emanates from a peripheral groove provided in the valve needle.

15. A needle valve according to Claim 12, wherein the compensating connection runs to the low-pressure region of the needle valve via a transverse bore and a central bore of the valve needle.

16 A needle valve according to Claim 12, wherein a valve conduit located on the low-pressure side is continued, via a bypass bore of smaller diameter, into a bottom space of a connecting bore located on the highpressure side.

17. A needle valve according to any one of Claims I to 16, wherein the guide bore and the valve needle have a larger diameter than the valve duct, the valve needle has a conical end region intended for engagement into the valve duct, and a seat surface for this conical end region of the valve needle is provided in the valve duct.

18. A needle valve according to Claim]7, wherein the difference in diameter is 15 to 20%.

19. A needle valve according to any one of Claims I to 18, wherein the stepping motor is assigned an electrical energy store and control electronics of an emergency power-generating system which are programmed, in the event of an interruption in a main power supply to the stepping motor, to make an emergency power connection between the stepping motor and the electrical energy store for the purpose of closing the needle valve, the electrical energy store and the control electronics being arranged in a housing also enclosing the stepping motor.

20. needle valve for a high-pressure gas conduit system, substantially as described herein with reference to and as illustrated in the accompanying drawings.